This is a long focus not a telephoto lens, there is a single group of elements at the front of the lens.

The Follow Focus lenses were based on the concept of modular parts, the most important of which was a pistol grip controlling the focus. The pistol grip housed a spring, when the trigger was squeezed the lens head was brought closer, when released the lens extended.

The lens came in several interchangeable parts, in the early 1970s these comprised:

• Pistol Grip. This was always present.
• Camera adapter. Several adapters were produced for different cameras. The standard adapter was a fixed length tube, this could be replaced by a shorter tube and a set of bellows that allowed closer focus.
• Lens Head. Three lenses were available, at this time, - 640 mm, 400 mm and 280 mm. The 280 mm fitted directly to the pistol grip. The 400 and 640 mm lenses fitted into a barrel containing the iris diaphragm (scales were present for both lenses, f5.6 - f32 and f9 - f32), these lenses were available complete (lens cell plus barrel) or the individual lens cell could be bought and fitted to an existing barrel. A lens hood was supplied with the 280 mm lens and as a component of 400 and 640 mm configurations (i.e. it was interchangeable between both lenses).

The special bellows unit attaches to the Pistol Grip tube, a camera adapter fits between the bellows and the camera. The adapter for use with the bellows is different to that used without bellows.

On early lenses the components screwed together later a bayonet was used.

The firm was founded in 1948 by Karl Müller, the Follow Focus system was introduced in 1955. As well as the lens system the company produced bellows and other accessories sold either under their own name or that of a camera manufacturer.

This is an early version of the Follow Focus lens where the units screw together rather than using a bayonet. The lens focal length is 300 mm a size that was later discontinued in favour of 280 mm.